Theophylline induced non specific suppressor activity in human peripheral blood lymphocytes

It is wellknown that theophylline yields phenotypic changes on suppressor cells. In the present study we investigated the possibility that theophylline could directly induce a suppressor activity on a lymphocyte subpopulation. We observed that a short preincubation (120 min at 37 degrees C) with theophylline (1mM) activates human peripheral blood lymphocytes to suppress mitogenic response of autologous cells. This activity was not evident on a T cell subpopulation depleted of theophylline-sensitive (T-sens) lymphocytes. Theophylline mediated suppressor activity is only present in the Concanavalin A stimulated cultures, thus suggesting a synergism between Concanavalin A and theophylline in the expression of non specific suppression. Moreover we observed that after a 24 hrs preincubation of lymphocytes in complete culture medium there was a complete loss of theophylline-induced suppression. Such a preincubation time also produced a decrease in the theophylline-mediated enhancement of intracellular 3', 5' cyclic adenosine monophosphate levels and the impairment of E-rosette formation, suggesting that theophylline acts mainly on a "short-lived" suppressor lymphocyte subset.